Locking device for withdrawable circuit-breakers

ABSTRACT

A locking device is for low-voltage circuit-breakers. It can travel into a frame including a lock and a control member to be activated through the lock. The control member interacts with an internal locking slide when a circuit-breaker is moved into the frame, the locking slide being displaceably guided in the circuit-breaker. If the locking device is activated (“locked”), the control member acts on the internal locking slide of the circuit-breaker and ensures that the circuit breaker cannot be switched on. If circuit-breakers with locking slides that can be displaced vertically are used, the control member is situated underneath the circuit-breaker.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/DE01/03176 which has an Internationalfiling date of Aug. 21, 2001, which designated the United States ofAmerica and which claims priority on German Patent Application numbersDE 100 44 530.6 and DE 101 04 325.2 filed Sep. 4, 2000, and Jan. 24,2001, respectively, the entire contents of each of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to a locking apparatus for low-voltagecircuit breakers. Preferably it relates to one which can be insertedinto a withdrawable part rack and has an internal locking slide. Theslide may be guided such that it can move linearly and connects alocking mechanism and an insertion opening for a drive crank and thelike to an internal connection readiness controller, which enablesconnection only when all the conditions required to do so are satisfied.

BACKGROUND OF THE INVENTION

A large number of devices are known for protection against incorrectoperation of circuit breakers. Conventional low-voltage circuit breakersgenerally have an internal locking slide, which is guided internallybehind the control panel of the circuit breaker and connects lockingmechanisms, insertion openings for drive cranks, pushbuttons, positionsignaling devices and the like to an internal connection readinesscontroller, which enables connection only when all the necessaryconditions are satisfied. For example, WO 99/56124 A1 discloses aswitching device having a locking device as well as a drive device forinsertion and withdrawal relative to a withdrawable part rack, in whichsaid devices can be operated only when the switching device is in thedisconnected state. A locking slide (locking rod) is guided by use ofelongated holes behind a control panel of the switching device, and hasa cam element which interacts with a driver of an OFF operating device.The driver and the cam element interact such that, during operation ofthe locking slide, the OFF operating device is drawn inward and in theprocess signals to the user that the switching device is locked in thedisconnected state.

A further possible way to provide protection against incorrect operationis described in DE 198 43 207 A1, which discloses a control panel for acircuit breaker, which has a user interface with an apparatus which canbe retrofitted for locking, concealing and designing control elements.This retrofitting process is achieved by use of a mounting plate, whichcan be mounted on the control panel, for holding further functionalgroups, with the mounting plate having attachment apparatuses for two ormore additional elements. One such additional element may be a lockingmechanism (locking cylinder).

All these known devices are, however, specific to the switch and areswitch-dependent, since they are components of the switch and, forexample, are removed together with the switch when the switch is removedfrom the switchgear assembly. When inserting a different switch, it isthus no longer possible to tell what switching state or what lockingconditions existed when the switch was removed. If the characteristicsdo not match, this can lead to danger in the assembly and to theoperator.

Thus, conventionally, a circuit breaker is in general locked in the“OFF” position by pushing and locking the disconnection button. The keyis withdrawn and the circuit breaker is locked in the OFF state, andcannot be connected. Nevertheless, it is possible for the circuitbreaker to be moved and to be removed in the withdrawable part in the“OFF” switch position.

SUMMARY OF THE INVENTION

An object of an embodiment of the present invention is to preventanother circuit breaker from being inserted into and connected in thatparticular withdrawable part rack. In this case, the main switchcondition should be satisfied, that is to say the position of theswitching contacts match the indicated position.

According to an embodiment of the present invention, an object may beachieved for a low-voltage circuit breaker which can be inserted into awithdrawable part rack in that the locking apparatus is arranged outsidethe circuit breaker and has an additional locking mechanism as well as acontrol element which interacts with the internal locking slide. Thisnecessarily ensures that a circuit breaker which has been inserted intothe withdrawable part rack cannot be connected if the locking apparatushas previously been operated.

According to an embodiment of the invention, the locking apparatus maybe designed such that if the locking slide is arranged such that it canmove vertically, the control element is arranged on a fixed-positioncomponent in a switch panel, which holds the circuit breaker, underneaththe circuit breaker. The desired interaction between the control elementand the locking slide can in this way be achieved in an operationallyreliable manner using simple means.

A compact and expedient refinement of the locking apparatus can beobtained by mounting this locking apparatus as a unit, which comprisesthe additional locking mechanism and the control element, in a switchpanel, which holds the circuit breaker, underneath the circuit breaker.The withdrawable part rack which holds the circuit breaker, or acrossmember of the switch panel which supports the withdrawable partrack are suitable components for attachment of the unit.

However, the locking apparatus may also be subdivided into functionalgroups, in this way creating the capability for the additional lockingmechanism to be arranged at a point on the switch panel that isparticularly suitable for the user. To this end, provision is made for acontrol unit which has the control element to be arranged on afixed-position component underneath the circuit breaker in the switchpanel, and for a locking unit, which is connected to the control unit bymeans of a flexible operating element and has the additional lockingelement, to be mounted in the switch panel at a distance from thecontrol unit.

In this context, it is desirable to be able to mount the control unit inthe switch panel as required. This can be achieved by the control unithaving a base plate with a control element which can pivot about abearing bolt on it, and having a resetting spring which prestresses thecontrol element into a rest position when the locking apparatus is inthe unactivated state.

The locking apparatus according to an embodiment of the invention on theswitchgear assembly side achieves the following function:

If any desired low-voltage circuit breaker which fits a withdrawablepart rack is inserted into that empty withdrawable part rack with thelocking apparatus on the switchgear assembly side operated, and is movedin the direction of the operating position, the locking apparatus on theswitchgear assembly side comes into effect on leaving the test positionand before reaching the operating position thereof. Thus, the controlelement, which is arranged in a fixed position, is located under anoperating surface of the internal locking slide of the circuit breaker.The locking slide is already raised by the withdrawn crank of theinsertion drive. When the operating position is reached, the crank canbe inserted back into the insertion drive. However, the control slideremains in its upper limit position, that is to say the “OFF” buttonremains depressed, and connection is not possible, because the controlslide is raised.

With the drive crank inserted and in the operating position, theadditional locking mechanism can be operated, hence raising or loweringthe locking slide, with the known effect. The additional lockingmechanism can thus be operated when the circuit breaker is in any of thepossible positions relative to the withdrawable part rack (disconnectedposition, test position or operating position or not fitted), but doesnot become effective until a circuit breaker is switched to theoperating position.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail in the following textwith reference, in order to assist understanding, to one preferredexemplary embodiment, although this does not restrict the scope ofprotection.

FIG. 1 shows, schematically, a low-voltage circuit breaker which has notbeen inserted into the withdrawable part rack, and a locking apparatuson the switchgear assembly side, which has not been operated.

FIG. 2 shows, schematically, a low-voltage circuit breaker which hasbeen inserted into the withdrawable part rack and is prevented frombeing connected by means of the locking apparatus according to anembodiment of the invention on the switchgear assembly side.

FIG. 3 shows examples of arrangements on the switchgear assembly side ofa locking apparatus.

A control unit which is suitable for the arrangement shown in FIG. 3 isillustrated in an enlarged perspective form in FIG. 4, and isillustrated in the form of a sectioned side view, in both positions, inFIGS. 5 and 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows, schematically, a low-voltage circuit breaker 2 which hasnot been inserted into a withdrawable part frame 1 and has a controlpanel 3, a locking slide 4 (cf. the locking rod 23 in EP 0 685 913 B1),which is guided such that it can move linearly internally behind thecontrol panel 3 of the circuit breaker 2 and connects a lockingmechanism 5 and an insertion opening (which is not illustrated) for adrive crank and the like to an internal connection readiness controller6, which enables connection only when all the necessary conditions aresatisfied (cf. DE 43 33 828 C1), as well as an unoperated lockingapparatus 7 on the switchgear assembly side, which comprises anadditional locking mechanism 8, which is fitted on the switchgearassembly side underneath the low-voltage circuit breaker 2, for exampleon the withdrawable part rack 1, having a withdrawable key 9 and acontrol element 10. When the locking apparatus 7 on the switchgearassembly side is in this unoperated state, the low-voltage circuitbreaker 2 can be inserted into the withdrawable part rack 1 without thelocking apparatus 7 on the switchgear assembly side coming into action,because the locking slide 4 on the switch side does not come intocontact with the control element 10. Switches can thus be removed andinserted in a desired manner, but only as a function of their internalcontrol and locking conditions.

FIG. 2 shows, schematically, a low-voltage circuit breaker 2 which hasbeen inserted into the withdrawable part rack 1 and is prevented frombeing connected by means of the locking apparatus 7 according to anembodiment of the invention on the switchgear assembly side. The lockingapparatus 7 on the switchgear assembly side operates the control element10 by way of the additional locking mechanism 8 during the lockingprocess. The control element 10 projects beyond the withdrawable partrack 1, and interacts with the internal locking slide 4 of the circuitbreaker 1 as follows:

If any desired circuit breaker 2 is inserted into an empty withdrawablepart rack 1 with the locking apparatus 7 on the switchgear assembly sideoperated, and is moved in the direction of the operating position, thelocking apparatus 7 on the switchgear assembly side becomes effective onleaving the test position and before reaching the operating position,that is to say the control element 10 which is located in thewithdrawable part rack 1 is located under an operating surface 11 of theinternal locking slide 4. The locking slide 4 has already been raised bythe withdrawn crank of the insertion drive. When the operating positionis reached, the crank can be pushed back into the insertion drive.However, the control slide remains in its upper limit position, that isto say the “OFF” button remains depressed and connection is impossiblebecause the control slide is raised. This normal function of theinternal locking slide 4 of the low-voltage circuit breaker 2 has notbeen illustrated, for the sake of clarity, since it is not significantto the invention.

FIGS. 1 and 2 show the locking apparatus 7 in the form of a unit, whichis mounted underneath the circuit breaker 2 on the associatedwithdrawable part rack 1 or on some other fixed-position component of aswitch panel which holds the withdrawable part rack together with thecircuit breaker. However, applications exist in which it appears to bemore advantageous or more expedient to operate the locking apparatus insome other position. This is made possible as shown in FIG. 3, whichdepicts another exemplary, non-limiting embodiment of the invention, byusing a locking apparatus 12 which is subdivided into functional groups,with the functional groups being connected to one another by use of ahinged or flexible operating element (rod linkage, cable run, Bowdencable).

FIG. 3 shows a locking unit 13, which contains the additional lockingmechanism 8, and a control unit 14 as the functional groups of thelocking apparatus 12, which are connected to one another by use of adifferently laid flexible operating element 15, depending on how thelocking unit 13 is fitted. The operating element 15 comprises, in aknown manner, a casing and a core which is guided in the casing. As isshown in FIG. 3, suitable positions for the locking unit 13 are, inparticular, a left-hand or right-hand side wall 16 or 17 of thewithdrawable part rack 1, a component 18 which supports the withdrawablepart rack 1 and is in the form of a crossmember, an intermediate wall ora drawer base of a switch panel 19, which holds the withdrawable partrack 1, or a door 20 which closes the switch panel 19. Thesearrangements are only examples. Those skilled in the art may thus alsochoose different positions if these appear to be more expedient to them.

The control unit 14 is the same for all the illustrated and otherpossible arrangements of the locking unit 13. It is located on afixed-position part, for example on the component 18 of the switch panel19 that has been mentioned or on the withdrawable part rack 1, providedthat this has a bottom plate, or the like. In order to make the controlunit 14 and the component 18 visible to the necessary extent in FIG. 3,the circuit breaker 2 is shown broken-open at the bottom. A part (whichinteracts with the control unit 14) of the locking slide 4 which isguided such that it can move linearly behind the control panel 3 canalso be seen in the broken-open area.

As can be seen in more detail in FIGS. 4, 5 and 6, the control unit 14has a base plate 21 with a bearing block 22 and a spring block 23.Openings 24 allow the control unit 14 to be mounted in any desiredmanner on said parts of the switch panel 19. A control element 25 is inthe form of a pivoting lever, which can move about a bearing bolt 26which is seated in the bearing block 22. A control tab 27 on the controlelement 25 at the same time forms an operating surface for theinteraction with the locking slide 4, and is used as an opposing bearingfor a resetting spring 28, whose other end is hooked in on the springblock 23.

As already mentioned, the flexible operating element 15 comprises acasing 30 and a core, which can be moved in it, in the form of a wirecable 31. The casing 30 is mounted on the control unit 14 via a holdingbracket 32, while a cap body 33 is provided at the opposite end (whichinteracts with the locking unit 13 in FIG. 3). The wire cable 31 iscoupled to the control element 25 via a fork body 34 which acts in ahinged manner on the control element and transmits the force exerted bythe wire cable 31 symmetrically to the control element 25.

FIG. 3 and the side view of the control unit 14 in FIG. 5 show theunactivated normal state of the locking apparatus 12, in which thecontrol element 25 assumes its rest position under the influence of theresetting spring 28, which is in the form of a tension spring. Theactivated state is illustrated by FIGS. 4 and 6, in which the controlelement 25 assumes a vertical position relative to the base plate 21. Inthis position, the control element 25 comes under the influence of thefork body 34 and of the wire cable 31, which is operated by the lockingunit 13, as is indicated in FIGS. 5 and 6.

An embodiment of the present invention ensures that a circuit breakerthat has been inserted is not moved accidentally or withoutauthorization to the operating position, where it can be connected. Thepreviously used locking apparatuses do not provide any protectionagainst this, since the locking apparatus is a component of the circuitbreaker and can be removed only together with it.

List of reference symbols 1 Withdrawable part rack 2 Low-voltage circuitbreaker 3 Control panel 4 Locking slide 5 Locking mechanism (on thecircuit breaker) 6 Connection readiness controller 7 Locking apparatus(FIGS. 1 and 2) 8 Locking mechanism of the locking apparatus 9 Key 10Control element (FIGS. 1, 2) 11 Operating surface 12 Locking apparatus(other embodiment, FIG. 3) 13 Locking unit 14 Control unit 15 Flexibleoperating element 16 Left-hand side wall of the withdrawable part rack 117 Right-hand side wall of the withdrawable part rack 1 18 Component ofthe switch panel 19 19 Switch panel 20 Door of the switch panel 20 21Base plate 22 Bearing block 23 Spring block 24 Through-hole 25 Controlelement (pivoting lever, FIGS. 4, 5, 6) 26 Bearing bolt 27 Control tabon the control element 25 28 Resetting spring 30 Casing of the operatingelement 15 31 Wire cable 32 Holding bracket 33 Cap body 34 Fork body

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. An arrangement comprising: plug-in unit; a low-voltage power switchinserted into the plug-in unit, and provided with an internal lockingslide which can be moved from a resting position to an activatedposition, wherein the locking slide controls an internal readinesscontroller; and a locking device fixed relative to the plug-in unit andincluding a lock for locking the internal locking slide in the activatedposition where an activation of the low-voltage power switch isprevented; and a control element that cooperates with the internallocking slide; wherein the control element is moveable from anon-activated first position to an activated second position; andwherein the lock functions to lock the control element in the activatedsecond position.
 2. The arrangement as claimed in claim 1, wherein thelocking slide is vertically moveable, the control element is arranged ona fixed-position component in a switch panel that holds the low-voltagepower switch, and the control element is located underneath thelow-voltage power switch.
 3. The arrangement as claimed in claim 2,wherein the locking device is mounted as a unit, the unit comprises thelock and the control element, the unit is mounted in the switch panel,and the unit is located underneath the low voltage power switch.
 4. Thearrangement as claimed in claim 2, wherein a control unit, including thecontrol element, is arranged on the fixed-position component underneaththe low-voltage power switch in the switch panel, and wherein a lockingunit, connected to the control unit via a flexible operating element andincluding the lock, is mounted in the switch panel, at a distance fromthe control unit.
 5. The arrangement as claimed in claim 4, wherein thecontrol unit comprises: a base plate with the control element adapted topivot about a bearing bolt on the base plate; and a resetting springwhich prestresses the control element into the non-activated positionwhen the locking apparatus is in an unactivated state.
 6. An arrangementcomprising: a plug-in unit; a low-voltage power switch insertable intothe plug-in unit and including an internal locking slide, movable from aresting position to an activated position, wherein the internal lockingslide controls an internal readiness controller; and a locking devicefixed relative to the plug-in unit and including a lock for locking theinternal locking slide in the activated position where an activation ofthe low-voltage power switch is prevented; and a control element thatcooperates with the internal locking slide; wherein the control elementis moveable from a non-activated first position to an activated secondposition; and wherein the lock functions to lock the control element inthe activated second position.
 7. The arrangement as claimed in claim 6,wherein the internal locking slide is vertically moveable, the controlelement is arranged on a fixed-position component in a switch panel thatholds the low-voltage power switch, and the control element is locatedunderneath the low-voltage power switch.
 8. The arrangement as claimedin claim 7, wherein the locking apparatus is mounted as a unit, the unitcomprises the lock and the control element, the unit is mounted in theswitch panel, and the unit is located underneath the low-voltage powerswitch.
 9. The arrangement as claimed in claim 7, wherein a controlunit, including the control element, is arranged on the fixed-positioncomponent underneath the low-voltage power switch in the switch panel,and wherein a locking unit, connected to the control unit via a flexibleoperating element and including the lock, is mounted in the switchpanel, at a distance from the control unit.
 10. The arrangement asclaimed in claim 9, wherein the control unit comprises: a base platewith the control element adapted to pivot about a bearing bolt on thebase plate; and a resetting spring which prestresses the control elementinto the non-activated first position when the locking apparatus is inan unactivated state.